[NET]: make netlink user -> kernel interface synchronious

This patch make processing netlink user -> kernel messages synchronious.
This change was inspired by the talk with Alexey Kuznetsov about current
netlink messages processing. He says that he was badly wrong when introduced 
asynchronious user -> kernel communication.

The call netlink_unicast is the only path to send message to the kernel
netlink socket. But, unfortunately, it is also used to send data to the
user.

Before this change the user message has been attached to the socket queue
and sk->sk_data_ready was called. The process has been blocked until all
pending messages were processed. The bad thing is that this processing
may occur in the arbitrary process context.

This patch changes nlk->data_ready callback to get 1 skb and force packet
processing right in the netlink_unicast.

Kernel -> user path in netlink_unicast remains untouched.

EINTR processing for in netlink_run_queue was changed. It forces rtnl_lock
drop, but the process remains in the cycle until the message will be fully
processed. So, there is no need to use this kludges now.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Acked-by: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 2 insertions, 2 deletions

diff --git a/include/linux/connector.h b/include/linux/connector.h
index 10eb56b2940a..b62f823e90cf 100644
--- a/include/linux/connector.h
+++ b/include/linux/connector.h
@@ -153,7 +153,7 @@ struct cn_dev {
 
         u32 seq, groups;
         struct sock *nls;
-        void (*input) (struct sock * sk, int len);
+        void (*input) (struct sk_buff *skb);
 
         struct cn_queue_dev *cbdev;
 };
diff --git a/include/linux/netlink.h b/include/linux/netlink.h
index 7b552b6c2c19..7c1f3b1d2ee5 100644
--- a/include/linux/netlink.h
+++ b/include/linux/netlink.h
@@ -175,7 +175,7 @@ struct netlink_skb_parms
 
 extern struct sock *netlink_kernel_create(struct net *net,
                                           int unit,unsigned int groups,
-                                          void (*input)(struct sock *sk, int len),
+                                          void (*input)(struct sk_buff *skb),
                                           struct mutex *cb_mutex,
                                           struct module *module);
 extern int netlink_change_ngroups(struct sock *sk, unsigned int groups);